Make Tip-taps (importance of hygiene) and water filters (importance of clean water) - 30 minutes for each activity.
Tip-taps - see attached. Water filters - see attached but can also use play sand (NOT sharp sharp), (crushed) lumpwood charcoal (not briquettes) and moss (or other green material).
See attached. For water filters, cut off the bottom of a 2L pop bottle and turn upside down. Place moss in the upturned bottle to provide a platform over the spout for the sand. Layer in sand (2-3 inches, crushed charcoal (use a ziplock bag, mallet and bash) 1-2 inches, sand (2-3 inches) and then moss (to stop the sand layer being disturbed). Carefully wash in clean water to flush it out, then try really muddy water - should be clear though likely to still be discoloured to some extent.